Fix broken windows CI

It turns out our cache was always missing because of backslashes in the cache keys.
The problem was exposed when I tightened up the non-hermetic action reads in https://github.com/bazelbuild/rules_typescript/commit/30d28943efa6ea3880879bcf7f11a3d455fcb4a6

PiperOrigin-RevId: 194609051
1 file changed
tree: 03fd18b346e9733d0f4edbfbb7a1598c18465f21
  1. packages/